Two-way band saw machine

ABSTRACT

To cut a workpiece along two different cutting directions, the band saw teeth are set horizontally by a band saw guide device and then the cutting head (CH) is moved frontward, for instance; thereafter, the band saw teeth are twisted downward by the same guide device and then the cutting head is moved downward. The machine is effectively usable in cutting off a test piece from a large workpiece. To improve the cutting precession, various novel devices are incorporated, such as a balance cylinder (B-CYL) for allowing the cutting head to move up and down smoothly; two back-and-forth cylinders (BF-CYL) for moving the cutting head back and forth in symmetrical pressure application; cutting head fix device (FD); a rigid guide column; band saw holding device (BSH); a slidable small-diameter driven wheel arranged within the cutting head (CH), etc.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a two-way band saw machine for cuttinga relatively large workpiece along two cutting planes.

2. Description of the Prior Art

Various band saw machines for cutting a workpiece have been well known.However, these conventional band saw machines can cut off a workpiecealong only a single cutting plane or in a predetermined direction.

Therefore, where a test piece a as shown in FIG. 1(A) is required to becut off from a workpiece A, two different workpiece setting works arerequired. That is, the workpiece A is first cut off into a long andnarrow piece aa as shown in FIG. 1(B) after a first workpiece setting,and then the cut off workpiece aa is further cut off into a final testpiece a as shown in FIG. 1(C) after a second workpiece setting. Wherethe dimensions and weight of the workpiece is large, the setting work islaborious, and the cutting precision is lowered when a large workpieceis moved to and fro.

Further, the remaining piece aaa as shown in FIG. 1(C) becomes wasteful.Furthermore, when a test piece b as shown in FIG. 1(D) is required to becut off from a workpiece B, it is impossible for the conventionalmachine to obtain the test piece b of this shape, for instance.

SUMMARY OF THE INVENTION

With these problems in mind, therefore, it is the primary object of thepresent invention to provide a two-way band saw machine which can cutoff a workpiece along two cutting planes without setting a workpiece ona worktable twice.

To achieve the above-mentioned object, a two-way band saw machine havinga worktable for mounting a workpiece thereon; a cutting head forsupporting an endless band saws a guide column for supporting thecutting head; and a base for supporting the worktable and the guidecolumn, according to the present invention, comprises: (a) means forselectively guiding part of endless band saw teeth toward a firstcutting direction and a second cutting direction; (b) means forproviding a first relative cutting motion between the cutting head andthe worktable in the first cutting direction; and (c) means forproviding a second relative cutting motion between the cutting head andthe worktable in the second cutting direction.

The band saw guiding means comprises a pivotal body supported by thecutting head; guide blocks slidably arranged within the pivotal body soas to pinch the flat surface of the band saw; a hydraulic cylinder foractuating the pivotal body to the first and second cutting directions;and a hydraulic cylinder for locking the pivotal body to the cuttinghead.

When the cutting head is arranged extending in the horizontal direction,the two cutting directions are horizontal and vertical directions. Inthis case, the cutting head includes a lift housing moved up and downalong the guide column and a band saw housing moved back and forthrelative to the lift housing, so that the cutting head is movable in twodirections relative to the fixed worktable.

To move the lift housing up and down, a balance hydraulic cylinderalways operated at a constant pressure to support the lift housing isincorporated in addition to the lift hydraulic cylinder for mainlymoving the lift housing up and down. The movable lift housing can befixed to the guide column by cutting head fixing means.

To move the band saw housing back and forth relative to the lifthousing, two back-and-forth cylinders are operated through a singlemaster cylinder having two equivolume pressure chambers simultaneouslyby the same pressure.

To increase the rigidity of the guide column, a plurality of guide postsand link members are effectively connected. Further, it is preferable toprovide the machine with band saw supporting means to facilitate removaland mounting of the band saw from or on the cutting head. To furtherfacilitate the removal and mounting of the band saw, the band saw isreeved around a large drive wheel and a pair of small drive wheels atleast one of which is slidably movable.

When the cutting head is arranged extending in the vertical direction,the first cutting direction is a back-and-forth direction and the secondcutting direction is a right-and-left direction. The cutting head ismoved relative to the worktable or the worktable is moved to the cuttinghead in either or both cutting directions.

In the two-way band saw machine according to the present invention atest piece can be cut off from a workpiece by setting the workpiece tothe machine only once. When the workpiece is heavy, since the workpiecesetting work is troublesome, the above-mentioned single workpiecesetting work is very convenient.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(A) to (D) are illustrations for assistance in explaining the ofthe two-way band saw machine according to the present invention;

FIG. 2(A) is a front view showing a first (horizontal) two-way bandmachine according to the present invention;

FIG. 2(B) is a side view of the same machine shown in FIG. 2(A);

FIG. 2(C) is a top view of the same machine shown in FIG. 2(A);

FIG. 3(A) is a front view showing the cutting head CH of the seen fromthe line IIIA--IIIA shown in FIG. 2(B);

FIG. 3(B) is a side view showing the same cutting head CH of themachine, seen from the line IIIB--IIIB shown in FIG. 3A;

FIG. 3(C) is a top view showing the same cutting head CH of the machine,seen from the line IIIC--IIIC shown in FIG. 3(A);

FIG. 4 is an enlarged bottom view of a lift housing fixing device FD ofthe machine, seen from the line IV--IV shown in FIG. 2(C);

FIG. 5(A) is an enlarged side view showing a lefthand band saw guideBSG(L), seen from the line VA--VA shown in FIG. 2(A);

FIG. 5(B) is an enlarged front, partially cross-sectional view showingthe same guide device BSG(L), taken along the line VB--VB shown in FIG.5(A);

FIG. 5(C) is a bottom view showing the same guide device BSG(L), fromthe line VC--VC shown in FIG. 5(B);

FIG. 6 is a hydraulic circuit diagram for operating a lift cylinder andtwo back-and-forth cylinders incorporated in the machine shown in FIGS.2(A), (B) and (C);

FIG. 7(A) is a diagrammatical side view showing a second (vertical)two-way band saw machine according to the present invention; and

FIG. 7(B) is a diagrammatical front view showing the same machine shownin FIG. 7(A).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the attached drawings, a first embodiment (horizontalband saw machine) of the present invention will be described, in which aband saw is supported horizontally and a cutting head is moved up anddown and back and forth relative to a worktable.

FIG. 2(A) is a front view thereof; FIG. 2(B) is a side view thereof; andFIG. 2(C) is a top view thereof. The horizontal band saw machine isroughly made up of a base BA on which a worktable WT is mounted, a viceVI mounted on the base BA to vise a workpiece W mounted on the worktableWT; a cutting head CH for supporting an endless band saw BShorizontally; and a guide column GC for supporting the cutting head CHso as to be movable both in the vertical and horizontal directions.

To cut a workpiece W into a predetermined block, a workpiece W ismounted on the worktable WT and then vised by the vice VI. Thereafter,when the band saw BS is held in such a way that the teeth thereof isdirected downward and the cutting head CH is lowered, the workpiece W iscut in the vertical cutting plane. On the other hand, when the band sawBS is held in such a way that the teeth thereof is directed frontward bytwisting the band saw partially with a hydraulic cylinder, for instanceand the cutting head CH is moved frontward, the workpiece W can be cutalong the horizontal cutting plane.

The base BA includes a main base 1 formed by combining H-shaped steelsor channel steels into a square shape, and a pair of right and leftsubbases 2R and 2L arranged on both the sides of the main base 1 so asto form a recessed space at the middle portion of the main base 1.

The worktable WT is made up of a plurality of sleepers (ties) 3 arrangedwithin the recessed space on the main base 1 extending in thefront-and-back direction, a pair of guide rails 4 arranged on thesleepers 3, a worktable WT slidably mounted on the rails 4 via wheels 5rotatably engaged with the rails 4, a plurality of pinch rollers 6 forpinching the guide rails 5 to restrict the movement of the worktable WTin the right and left direction (perpendicular to the rails). Inaddition, a rack rod 7 is fixed to the inside of the worktable WT inparallel to the guide rails 4, and a pinion gear 8 driven by aservomotor M is in mesh with the rack rod 7. Therefore, when the piniongear 8 is driven by the servomotor M, the worktable WT can be moved backand forth. Further, the position of the worktable WT can be detected byan appropriate position detector (not shown) and be positioned at adesired location by feedback control. The worktable WT is moved tolocate a workpiece W mounted thereon at an appropriate cutting position.

The vice VI comprises a reference vice 10R slidably mounted on the rightsubbase 2R and a push vice 10L also slidably mounted on the left subbase2L. These two vices are arranged so as to vise a workpiece W mounted onthe worktable WT from both the sides thereof. The reference vice 10Rincludes a support slider llR slidably engaged between two guide members12R fixed on the right subbase 2R. The push vice 10L includes a supportslider 11L slidably engaged between two guide members 12L fixed on theleft subbase 2L. Although not shown, these two vices can be moved backand forth in synchronism with each other by an appropriate actuator suchas rack-pinion mechanism, hydraulic cylinder, etc. to an appropriateposition at which a workpiece on the worktable can be vised firmly.

To vise a workpiece mounted on the worktable WT, a pair of slide bars13R are slidably passed through the support slider 11R horizontally, anda reference vice jaw 14R is fixed to the slide bars 13R. A pair of slidebars 13L are slidably passed through the support slider 11L, and a pushvice jaw 14L is also fixed to the slide bars 13L.

To move the reference vice jaw 14R to and fro, a minicylinder M-CYL isdisposed in the support slider 11R in such a way that a top end of apiston rod thereof is connected to the reference vice jaw 14R. On theother hand, to move the push vice jaw 14L to and fro, a hydraulic motorHM is fixed on a cover bracket 15 in such a way that one end of thescrew rod 16 is connected to the hydraulic motor HM and the other endthereof is engaged with a nut member 17 fixed to the support slider 11L.

Therefore, when the minicylinder M-CYL is actuated or deactuated, thereference vice jaw 14R can be moved to and fro by the cylinder rod; andwhen the hydraulic motor HM is driven, the push vice jaw 14L can bemoved to and fro via the screw rod 16 and the nut member 17. That is, aworkpiece W can be vised by or released from these two vice jaws 14R,14L. Further, both the support sliders 11R and 11L can be moved back andforth in synchronism with each other when a workpiece W is vised betweenthe two, or independently when a workpiece W is not vised.

The guide column GC for supporting the cutting head CH comprises acylindrical main guide post 20 vertically fixed on the right subbase 2R,a square subguide post 21 vertically fixed on the left subbase 2L, andtwo square rear posts 22R and 22L vertically disposed behind the mainand subguide posts 20 and 21, respectively, as shown in FIG. 2(C).

To further increase the rigidity of the guide column GC, as shown inFIG. 3(A), (B) and (C), a lower link member 23R is connected between themain guide post 20 and the rear post 22R; a lower link member 23L isconnected between the subguide post 21 and the rear post 22L. Inaddition, as shown in FIGS. 2(A) and 2(B), an upper link member 24R isconnected between the main guide post 20 and the rear post 22R; an upperlink member 24L is connected between the subguide post 21 and the rearpost 22L.

Furthermore, an intermediate link member 25 is connected between the twoupper link members 24R and 24L, as shown in FIG. 2(A).

In the above guide column construction, since the main guide post 20 andthe subguide post 21 are reinforced by the rear posts 22R and 22L, evenif the cutting head CH is moved back and forth and therefore a largemoment is generated, it is possible to prevent bending of the main andsubguide posts, thus allowing the cutting head CH to smoothly move upand down. Further, since the main and subguide posts 20 and 21 areconnected by the intermediate link member 25, when the cutting head CHis unbalanced in weight in the right and left direction, it is possibleto prevent bending of the main and subguide posts 20 and 21.

With reference to FIGS. 2(A) and (B), the cutting head CH for supportinga band saw BS comprises a lift housing 30 movable up and down beingguided along the main guide post 20 and the subguide post 21 and a bandsaw housing 31 movable back and forth being supported by the lifthousing 30.

In more detail, with reference to FIGS. 3(A) and (C), the lift housing30 has right and left leg members 30H and 30L connected by a beam 30a.The right leg member 30R is fitted to the main guide post 20 movably upand down. The left leg portion 30L is positioned a little rightward fromthe leftmost end of the beam member 30a.

A guide bracket 54L is fixed to the left leg member 30L, and two rollerbrackets 32 are fixed to the leftmost end of the beam member 30a. A pairof guide rollers 33 are rotatably supported by each roller bracket 32 soas to pinch a vertical guide rail 34 fixed to the inside surface of thesubguide post 21 from the front and back direction. Further, a verticalposition sensor 35 (shown in FIG. 3C) such as a rotary encoder ismounted on the beam member 30a. This sensor 35 has a pinion driven by arack rod 35a fixed to the subguide post 21 in parallel to the lift guiderail 34. Therefore, when the lift housing 30 is moved up and down alongthe main guide post 20 and the subguide post 21, the up-and-downposition and the up-and-down movement speed of the lift housing 30 canbe detected by the vertical position sensor 35.

To move the lift housing 30 up and down, a lift cylinder L-CYL isarranged near the main guide post 20, while a balance cylinder B-CYL isarranged near the subguide post 21, as depicted in FIG. 3(A). The baseportion of the lift cylinder L-CYL is fixed to the subbase 2R, while themovable end portion thereof is linked to a bracket 36R fixed to the beammember 30a. The base portion of the balance cylinder B-CYL is fixed tothe subbase 2L, while the movable end portion thereof is fixed to abracket 36L fixed to the beam member 30a. This balance cylinder B-CYLserves to support a moment of the lift housing 30 to allow the legmember 30R of the lift housing 30 to more smoothly move up and downalong the main guide post 20. The diameter of this balance cylinderB-CYL is smaller than that of the lift cylinder L-CYL. The hydraulicpressure of the balance cylinder B-CYL is always kept constant so as tosupport a moment of the cutting head CH.

Therefore, when the lift cylinder L-CYL is operated, the lift housing 30is moved up and down, and a moment of the lift housing 30 is supportedby the balance cylinder B-CYL.

To fixed the movable lift housing 30 at any given height, a lift housingfixing device FD is provided, as shown in FIGS. 2(C) and 3(C), betweenthe guide column GC and the lift housing 30. In more detail, in FIG. 4,a clevis bracket 40 is fixed to the upper link member 24R connecting themain guide post 20 and the rear post 22R with bolts. A support member 41made up of a plurality of band steel plates spaced by annular spacers 42is fixed to this clevis bracket 40 with bolts and nuts. On the otherhand, a U-shaped bracket 43 is fixed to the lower link member 23R alsoconnecting the main guide post 20 and the rear post 22R with bolts. Thelower portion of the support member 41 is connected to the U-shapedbracket 43 via annular spacers 44 and a tubular elastic member 45 suchas urethane rubber.

To fix the lift housing 30 to the support member 41 by friction, abracket 46 is fixed to the lift housing 30 so as to face the supportmember 41. A base block 47 is fixed to this bracket 46 with bolts. Apair of support leg members 47a are fixed to this base block 47, and alift lock cylinder LO-CYL is mounted on this support member 41. A pushblock 48 is attached to an end of a piston rod 49 of the cylinderLO-CYL. A plurality of friction members FC intervene between the pushblock 48 and the support member 41 and between two support members 41and between the support member 41 and the base block 47. These frictionmembers FC are slidably supported within grooves formed in the supportleg member 47a to restrict the vertical motion of the friction membersFC.

When the lift lock cylinder LO-CYL is operated to strongly push thefriction members FC and the support member 41 via the push block 48,since the friction members FC and the support members 41 are stronglypinched therebetween, the bracket 46 is friction locked to the supportmember 41. Therefore, the lift housing 30 is fixed to the support member41 (i.e. the guide column) for safety when the lift cylinder L-CYL is introuble, for instance.

Without being limited to the device shown in FIG. 4, various methods canbe adopted. For instance, the lift housing 30 may be clamped directly,or an additional clamp post is provided for clamping operation only, ora wirerope or steel band is connected to the lift housing 30 so as to beclamped. To actuate the clamping device, hydraulic pressure or motor andgear mechanism can be used. In this case, friction force obtained byelastic members is utilized. The elastic members are released forclamping by actuating the device or urged for unclamping by deactuatingthe device or vice versa.

With reference to FIGS. 3(A), (B) and (C), to move the band saw housing31 back-and-forth relative to the lift housing 30, a pair ofback-and-forth cylinders BF-CYL(R) and (L) are provided.

As best shown in FIG. 3(B), a guide brackets 50 provided with a guidemember 51 are disposed at both upper and lower portions of the legmember 30R of the lift housing 30. In the same way, as shown in FIG.3(A) a guide bracket 52 provided with a guide member 53 is disposed onthe upper portion of the leg member 30L of the lift housing 30, and aguide bracket 55 provided with a guide member 53 is disposed on thelower portion of the leg member 30L.

Further, a slide member 54R is located between the two upper and lowerguide members 51 extending in the horizontal direction of the band sawhousing 31. A slide member 54L is located between two upper and lowerguide members 53 extending in the same horizontal direction.

Further, a back-and-forth cylinder BF-CYL(R) is disposed on the guidebracket 50, a back-and-forth cylinder BF-CYL(L) is disposed at the lowerportion of the leg member 30L. Two piston rods, of these cylinders arein contact with the back surface of the band saw housing 31, andactuated in synchronism with each other.

To detect the position and the movement speed of the saw housing 31 inthe back-and-forth direction, a rack rod 55 (FIG. 3B) is fixed to theslide member 54R so as to engage with a pinion gear of a position sensor56 such as an encoder mounted on the guide bracket 50.

Therefore, when the back-and-forth cylinders BF-CYL(R) and (L) areoperated, the band saw housing 31 is moved back and forth relative tolift housing 30. Further, the back-and-forth position and the movementspeed is detected by the position sensor 56.

As shown in FIG. 2(A), the saw housing 31 is provided with a beam member60 extending in a right and left direction and a pair of right and leftwheel housings 61R and 61L of hollow box type as shown in FIG. 2(A). Theslide members 54R and 54L are fixed to the rear walls of the wheelhousings 61R and 61L, respectively. Top ends of the piston rods of theback-and-forth cylinders BF-CYL(R) and (L) are in contact with the rearwalls of the wheel housings, respectively.

Within the wheel housing 61R, a large-diameter wheel 62 and a drivengear 63 are rotatably housed via a shaft 64 as shown in FIG. 2(A). Thisdriven gear 63 is in mesh with a drive gear 65 driven by a motor M via areduction gear RG shown in FIG. 2(B).

On the other hand, within the wheel housing 61L, two small-diameterwheels 66U and 66L are rotatably housed via shafts 67U and 67L. Theupper shaft 67U is supported by a slide block 68 and the lower shaft 67Lis supported by the rear plate of the wheel housing 61L. The slide block68 is further slidably supported by a guide block 69. To slide the slideblock 68 to and fro, a tension cylinder TN-CYL is mounted on the guideblock 69 in such a way that an end of the piston rod of this cylinder isin contact with the slide block 68.

Therefore, after an endless band saw BS is reeved around the drive wheel62 and the two driven wheels 66U and 66L, if the tension cylinder TN-CYLis operated to move the upper driven wheel 66U in the leftward directionin FIG. 2(A), an appropriate tension is applied to the band saw BS.Further, it is preferable to always urge the wheel 66U leftward by anelastic member.

As described above, since two small-diameter driven wheels 66U and 66Lare arranged a distance away from each other, it is possible to reducethe longitudinal length of the saw housing 31 and therefore reduce thesize and weight of the cutting head CH. Further, since the upper drivenwheel 66U is slidable, the band saw BS can be loosened easily forproviding an easy removal of the band saw from the saw housing 31.

To facilitate the replacement of the band saw, there are provided sideopenable cover 70R and 70L, upper openable covers 71R and 71L, and loweropenable covers 72R and 72L are provided for the wheel housings 61R and61L.

To further facilitate replacement of the band saw, a band saw holder BSHis provided for the band saw housing 31. In more detail, with referenceto FIGS. 2(A) and 2(B), two support brackets 80R and 80L are fixed tothe front surface of the beam member 60. Two saw suspending cylinders81R and 81L are pivotally supported by two pins on the brackets 80R and80L, respectively, as depicted in FIG. 2(B). A band saw support member82 of L-shaped cross section extending in the right and left directionis supported by two piston rods of the two cylinders 81R and 81L, so asto support the upper straight portion of the endless band saw BS betweenthe drive wheel 62 and two driven wheels 66U and 66L. Further, two bandsaw holding plates 83 are mounted at the lower end of the support member82.

To set the endless band saw BS to the wheels, the upper portion of theendless band saw is put on the holding plate 83 and the lower portionthereof is set to the drive wheel 62 and the lower driven wheel 66L.Thereafter, the two saw suspending cylinders 81R and 81L are operatedsimultaneously to lift the holding plate 83 to the upper position inflush with the upper portion of the driven wheel 66U, and then thesupport member 82 is pivoted backward toward the wheels 62 and 66U toput the band saw on these two wheels. To remove the band saw BS from thewheels, the above procedure is reversed. Therefore, even if the band sawis large and heavy, it is possible to easily mount or remove the bandsaw.

To guide the band saw BS into two, vertical and horizontal position, thewheel housings 61R and 61L are provided with two band saw guide devicesBSG(R) and (L), respectively. The righthand guide device BSG (R) isfixed to lower portion of the righthand wheel housing 61R. The lefthandguide device BSG(L) is slidably supported by the lefthand wheel housing61L so as to be adjustable according to the width of a workpiece W to becut. Further, a rotary brush RB is rotatably attached to the righthandband saw guide device BSG(R) to remove chip from the band saw BS. Thisbrush RB is driven by a drive wheel 62 in conventional way. Further,chip removed by the brush is fed out by a conveyer CON shown in FIG.2(B).

The lefthand band saw guide device BSG(L) will be described in detailwith reference to FIGS. 5(A), (B) and (C). The device BSG(L) includes amovable arm 100 and a box-shaped guide housing 101 fixed to the arm 100with bolts. As shown in FIG. 5(B), the guide housing 101 is formed witha circular arc-shaped opening 101A(R) and a circular arc-shaped groove101B concentrically to the opening 101B at the lower portion of a rightside plate thereof. Further, the guide housing 101 is formed with acircular arc-shaped opening 101A(L) at the lower portion of a left sideplate thereof. At this opening 101A(L), a circular arc-shaped guidemember 102 formed with a circular arc-shaped guide groove 101B(L) isfixed. A pivotal body PB is engaged with these two grooves 101B(R) and(L) as depicted in FIG. 5(B).

As shown in FIG. 5(A), this pivotal body PB is formed with a groove 103to which the band saw BS is inserted. Within this groove 103, two guideblocks 104 are opposingly disposed to pinch the band saw BS when pushedagainst each other by a minicylinder M-CYL. Further, within the groove103, a back support block 105 for supporting the rear side of the bandsaw 11 is mounted via a pin 106.

Further, as shown in FIG. 5(C), a pair of pinch rollers 107 and 108 aredisposed to pinch the band saw BS. The roller 108 is rotatably supportedby a pivotal bracket 109 supported by a pin. This pivotal bracket 109 isurged toward the roller 107 by a minicylinder M-CYL mounted on thepivotal body PB.

As described above, the band saw BS is supported by the rollers 107 and108 and the guide blocks 104 on both the flat sides and by the block 105on the back side.

To direct the band saw BS in the vertical and horizontal directions, apivotal cylinder P-CYL is connected to the pivotal body PB. The baseportion of this cylinder is linked to the guide housing 101 and thepiston rod thereof is linked to the pivotal body PB.

To restrict the pivotal position of the pivotal body PB, a stopper pin110 is fixed to the top of the pivotal body PB so as to be brought intocontact with stopper bolts 111 (only one is shown) fixed to bracketsfixed to the guide housing 101 for pivotal position adjustment.

To lock the pivoted pivotal body PB, a lock cylinder L-CYL (FIG. 5B) isdisposed on the guide member 102. A piston 112 of this cylinder islinked with a pinch member 113 with a bolt. A spring 114 is disposedbetween the piston 112 and the pinch member 113 to unlock the pivotalbody PB.

Therefore, when the pivotal cylinder P-CYL is operated, the pivotal bodyPB is pivoted by a right angle to direct the tooth portion of the bandsaw toward the vertical or horizontal direction. Thereafter, when thelock cylinder L-CYL is operated, the pivotal body PB is fixed betweenthe pinch member 113 and the guide member 102.

In place of the pivotal cylinder P-CYL, it is of course possible toincorporate a motor and gear mechanism or other.

The construction of the righthand band saw guide device BSG(R) is almostthe same as that of the above-mentioned lefthand band saw guide deviceBSG(L) except the pivotal body, the description thereof being omittedherein.

FIG. 6 shows a hydraulic circuit for controlling the lift cylinderL-CYL, the balance cylinder B-CYL, and two back-and-forth cylindersBF-CYL(R) and (L).

When a solenoid SOL1 of the first solenoid valve SV1 is energized,hydraulic pressure is supplied from a pump P driven by a motor M to thelift cylinder L-CYL via a pilot operated check valve POCV through toraise the cutting head CH. Simultaneously, hydraulic pressure issupplied to the balance cylinder B-CYL via a balance valve BV to raisethe cutting head CH. When the cutting head CH moves upward and actuatesan upper limit switch LS1 on the guide column GC, the solenoid SOL1 ofthe first solenoid valve SV1 is deenergized to neutralize the firstsolenoid valve SVl, so that the cutting head CH stops moving.

Thereafter, when a solenoid SOL2 of the first solenoid valve SV1 isenergized, the pressure within the lift cylinder L-CYL is released bythe weight thereof, so that the cutting head CH comes down.

During the down-movement of the cutting head CH, the pressure within thebalance cylinder B-CYL rises because the weight of the cutting head CHis applied to the cylinder B-CYL. However, this pressure is released toa tank T via a balance valve BV.

When the cutting head CH comes down and therefore the band saw BSapproaches the workpiece W to a position at which cutting immediatelystarts, a lower limit switch LS2 is actuated to deenergize the secondsolenoid SOL2, so that the first solenoid SV1 is neutralized.

Further, when the lower limit switch LS2 is actuated, a third solenoidSOL3 of a second solenoid valve SV2 is switched to energization.Therefore, pressure within the lift cylinder L-CYL is discharged intothe tank T via two control valves FRV and AFRV. That is, the dischargerate of oil from the lift cylinder L-CYL is controller through a flowrate control valve FRV and an automatic flow rate control valve AFRV tocontrol the downward speed of the cutting head CH or band saw cuttingspeed.

Under control of the cutting speed, in case cutting speed increases or aback force component applied to the band saw increases excessively dueto abrasion of saw, a relief valve RV tends to be closed, so thatpressure within a left hand chamber 300 of the automatic flow ratecontrol valve AFRV rises to push a spool 301 against a balance spring302. Therefore, the automatic flow rate control valve AFRV decreases theflow rate, so that the lowering speed of the cutting head CH decreasesto prevent bending or breakage of the band saw BS. When the back forcecomponent of the saw decreases, since the spool 301 is returned by thespring 302, the opening rate of the valve AFRV is returned to the normalstate, and therefore the lowering speed of the cutting head CH iscontrolled by the valve FRV.

To move the cutting head CH frontward, the back-and-forth cylindersBF-CYL(R) and (L) are operated. For doing this, when a solenoid SOL6 ofa fourth solenoid valve SV4 is energized, hydraulic pressure is suppliedfrom the pump P to a master cylinder M-CYL via a pilot operated checkvalve POCV, so that a piston rod 310 is moved rightward in FIG. 6.Therefore, pressure within two chamber 311R or 311L is supplied to thefirst pressure chamber 312R or 312L of the two back-and-forth cylindersBF-CYL(R) and (L), respectively, so that two cylinders moves the sawhousing frontward in synchronism with each other.

When the saw housing SH moves frontward, and therefore the band saw BSapproaches the workpiece W to a position at which cutting immediatelystarts, a back limit switch LS3 is actuated to switch the solenoid valveSV8 to a closed state. Further, a solenoid SOL4 of a third solenoidvalve SV3 is energized into an open state. Therefore, the furtherfrontward movement of the saw housing SH is controlled by the flow ratecontrol valve FRV and the automatic flow rate control valve AFRV in thesame way as when the saw housing SH is lowered. That is, the cuttingspeed of the band saw moving in the horizontal direction can becontrolled.

As described above, when the saw housing SH moves frontward, theworkpiece W can be cut horizontally. When the saw housing SH moves to astroke end, the limit switch LS4 is actuated. When this limit switch LS4is actuated, the third solenoid valve SV3 is switched into a closedstate; a solenoid SOL5 of the fourth solenoid valve SV4 is energized;and the solenoid valve SV8 is returned to an open state. Therefore,hydraulic pressure of the pump P is supplied to the second pressurechambers 313R and 313L to return the saw housing to the originalposition. When the saw housing is returned, a limit switch (not shown)is actuated to neutralize the forth solenoid valve SV4.

Further, it is possible to replenish the hydraulic pressure of the firstpressure chambers 312R and 312L of the two back-and-forth cylindersBF-CYL(R) and (L), by energizing a solenoid SOL8 of the sixth solenoidvalve SV6 and a solenoid SOL7 of fifth solenoid valve SV5 to open thevalves. Further, it is possible to lock the saw housing SW at therearward position by increasing the pressure applied to the secondpressure chambers 313R and 313L of the back-and-forth cylindersBF-CYL(R) and (L) by energizing a solenoid SOL9 of the seventh valveSV7. For doing this, the seventh solenoid valve SV7 is energized open.

Further, in FIG. 6, POCV denotes a pilot operated check valve; F denotesa filter; 0 denotes an orifice; PR denotes a pressure regulator.

In operation of the two-way band saw machine, a workpiece W is firstplaced on a worktable WT. In this case, the worktable WT can be adjustedin the front and back direction by moving the worktable WT along theguide rails 4. After the worktable WT is located at an appropriateposition, the workpiece WT is vised by the vice VI movable also in thefront and back direction.

After the workpiece W has been vised, the band saw teeth are directedfrontward by actuating the band saw guide and the cutting head CH ismoved frontward to a predetermined position and then moved backward tocomplete the first cutting operation. Thereafter, the band saw teeth aredirected downward by actuating the band saw guide and the cutting headCH is moved downward to a predetermined height to complete the secondcutting operation.

FIGS. 7(A) and 7(B) shows a second embodiment (vertical band sawmachine) of the present invention. In this embodiment, the cutting headCH is arranged vertically so as to be movable back and forth, and theworktable WT is movable to and fro. Although not shown, the band saw BScan be directed toward two intersecting direction by an appropriatepivotal body.

When the band saw BS is twisted at right angle as shown in FIG. 7(A) andthe cutting head CH is moved back and forth relative to a fixedworkpiece WT, the workpiece W is cut in the transversal direction of thebase BA; while when the band saw BS is not twisted as shown in FIG. 7(B)and the workpiece W mounted on a worktable WT is moved in thelongitudinal direction of the base BA relative to a fixed cutting headCH, the workpiece W is cut in the longitudinal direction of the base BA.This vertical type is convenient when a plate workpiece W is required tobe cut into a square or rectangular shape.

Without being limited to the above embodiments, the cutting head ismoved relative to the worktable or the worktable is moved to the cuttinghead in either or both cutting directions.

In the two-way band saw machine according to the present invention,since the band saw teeth are selectively guided toward first and secondcutting directions, it is possible to cut off a test piece from aworkpiece by two continuous cutting operations, after the workpiece hasonce been set to the machine, thus reducing the number of workpiecesetting works which are troublesome when the workpiece is heavy.

What is claimed is:
 1. A two-way band saw machine having a worktable(WT) for mounting a workpiece (W) thereon; a cutting head (CH) forsupporting an endless band saw (BS), and a base (BA) for supporting theworktable, which comprises:(a) means (BSG) for selectively twisting partof endless band saw teeth toward a first vertical cutting direction anda second horizontal cutting direction; (b) means for providing a firstrelative cutting motion between the cutting head and the worktable inthe first vertical cutting direction; (c) means for providing a secondrelative cutting motion between the cutting head and the worktable inthe second horizontal cutting direction and wherein; the cutting head(CH) comprises a lift housing (30) and a band saw housing (31); and saidmeans for providing a first relative cutting motion between the cuttinghead and the worktable comprises: (a) a lift hydraulic cylinder (L-CYL)for moving the lift housing up and down along a guide column providednear one end of the cutting head; and (b) a balance hydraulic cylinder(B-CYL) for supporting the lift housing always at a constant pressurenear the other end of the cutting head to smoothly move the cutting headalong the guide column.
 2. The two-way band saw machine as set forth inclaim 1, wherein said selective band saw twisting means (BSG)comprises:(a) a pivotal body (PB) pivotally supported by the cuttinghead (CH); (b) a pair of guide blocks (104) slidaly arranged within thepivotal body so as to pinch a flat surface of the band saw (BS); (c)means (P-CYL) for actuating said pivotal body (PB) to direct part ofendless bandsaw teeth toward the first and second cutting directions;and (d) means (L-CYL) for locking said actuated pivotal body to thecutting head at the first or second cutting position.
 3. The two-wayband saw machine as set forth in claim 2, wherein said selective bandsaw twisting means (BSG) further comprises a pair of pinch rollers (107,108) for pinching the band saw, one of the rollers being pivotallysupported by said pivotal body (PB) and urged against the mate rollerwith the band saw pinched therebetween.
 4. The two-way band saw machineas set forth in claim 1, wherein said selective band saw twisting means(BSG) is adjustably slidable along a longitudinal direction of theendless band saw.
 5. The two-way band saw machine as set forth in claim1, wherein said means for providing a first relative cutting motionfurther comprises means (FD) for fixing the cutting head to the guidecolumn, when the cylinder head is positioned at a predetermined height.6. The two-way band saw machine as set forth in claim 5, wherein saidcutting head fixing means (FD) comprises:(a) a plurality of plates (41)arranged vertically and fixed to the guide column; (b) a plurality offriction member (FC) arranged also vertically and fixed to the cuttinghead so as to pinch each of said plates therebetween; and (c) ahydraulic cylinder (LO-CYL) for urging the friction members against saidplates into frictional contact relationship between the two.
 7. Thetwo-way band saw machine as set forth in claim 1, wherein the endlessband saw is reeved around a large-diameter drive wheel (62) arranged onone side of the cutting head and two small-diameter driven wheels (66U,66L) arranged on the other side of the cutting head, at least one ofdriven wheels being slidable for providing an easy removal and mountingof the band saw from or to the cutting head.
 8. The two way band sawmachine as set forth in claim 1, wherein the cutting head (CH) isarranged extending in the vertical direction, with the cutting headbeing movable back and forth relative to the worktable and the worktablebeing movable to and fro relative to the cutting head.
 9. A two-way bandsaw machine having a worktable (WT) for mounting a workpiece (W)thereon; a cutting head (CH) for supporting an endless band saw (BS),and a base (BA) for supporting the worktable, which comprises:(a) means(BSG) for selectively twisting part of endless band saw teeth toward afirst vertical cutting direction and a second horizontal cuttingdirection; (b) means for providing a first relative cutting motionbetween the cutting head and the worktable in the first vertical cuttingdirection; (c) means for providing a second relative cutting motionbetween the cutting head and the worktable in the second horizontalcutting direction; wherein the cutting (CH) comprises a lift housing(30) and a vband saw housing (31); and said means for providing a secondrelative cutting motion between the cutting head and the worktablecomprises a pair of right and left hydraulic back-and-forth cylinders(BF-CYL (R), (L)) for moving the band saw housing back and forthrelative to the lifting housing, said cylinders being operated through asingle master hydraulic cylinder (M-CYL) having two equivolume pressurechambers and operated synchronously by the same pressure.
 10. A two-wayband saw machine having a worktable (WT) for mounting a workpiece (W)thereon; a cutting head (CH) for supporting an endless band saw (BS),and a base (BA) for supporting the worktable, which comprises:(a) means(BSG) for selectively twisting part of endless band saw teeth toward afirst cutting direction and a second cutting direction; (b) means forproviding a first relative cutting motion between the cutting head andthe worktable in the first cutting direction; (c) means for providing asecond relative cutting motion between the cutting head and theworktable in the second cutting direction; which further comprises aguide column (GC) comprising: (a) a main guide post (20) verticallydisposed on a base (BA); (b) a subguide post (21) vertically disposedapart from the main guide post in the right and left direction of themachine; (c) a pair of rear subguide posts (22R, 22L) arranged adistance apart from the main and subguide post, respectively, in therearward direction; (d) a pair of lower link members (23R, 23L)connected between the main guide post and the rear subguide post andbetween the subguide post and the rear subguide post, respectively, atthe lower portion thereof; (e) a pair of upper link members (24R, 24L)connected between the main guide post and the rear subguide post andbetween the subguide post and the rear subguide post, respectively, atthe upper portion thereof; and (f) an intermediate link member (25)connected between the two upper link members extending in the right andleft direction of the machine.
 11. A two-way band saw machine having aworktable (WT) for mounting a workpiece (W) thereon; a cutting head (CH)for supporting an endless band saw (BS), and a base (BA) for supportingthe worktable, which comprises:(a) means (BSG) for selectively twistingpart of endless band saw teeth toward a first cutting direction and asecond cutting direction; (b) means for providing a first relativecutting motion between the cutting head and the worktable in the firstcutting direction; and (c) means for providing a second relative cuttingmotion between the cutting head and the worktable in the second cuttingdirection; wherein said cutting head (CH) comprises means (BSH) forpivotally holding one straight portion of the endless band sawincluding: (a) pivotal cylinders (81R, 81L) pivotally supported by thecutting head, each of said cylinders having a cylinder rod; and (b) sawsupport members (82) attached to each cylinder rod of said pivotalcylinders for providing an easy replacement of the band saw relative tothe cutting head.